Many high-volume consumer products such as mobile devices and motor vehicles now include at least one digital camera. For example, FIG. 1 shows a mobile device 190 having a camera module 180 integrated therein. Camera module 180 includes an image sensor 100 beneath an imaging lens 170.
FIG. 2 is a cross-sectional view of image sensor 100. Image sensor 100 includes a semiconductor layer 202, a color filter array (CFA) 220A, and a microlens array 230A. Semiconductor layer 202 includes a pixel array 210A, which includes a plurality of pixels 210 that each have a photodiode region 212. Microlens array 230A includes a plurality of microlenses 230. A photodiode isolation structure 204 is between adjacent photodiode regions 212.
Each photodiode region 212 extends a distance 212H from a top surface 202T from semiconductor layer 202. Distance 212H is for example twenty micrometers beneath a color filter 220(R) to allow for sufficient absorption of red light within photodiode region 212.
Color filters 220 are typically dye filters that absorb one or more wavelength ranges of visible light such that each pixel 210 is characterized by one or more wavelength bands of visible light to which it responds, e.g., red, green, blue, cyan, magenta, and yellow. In FIG. 2, each color filter 220 is one of a red (R), green (G), and blue (B) filter, denoted by 220(R), 220(G), and 220(B), respectively. Each color filter 220 as a height 220H. In addition to distance 212H, height 220H limits how thin image sensor 110 can be, which in turn limits its value in devices where compactness is a key functional and/or value-added feature.